1. Field of the Invention
The invention relates to an integrated circuit (IC) and, particularly, the invention relates to an IC which includes a seal ring.
2. Description of Related Art
In general, fabrication of integrated circuits may have three steps such as a fabrication of a silicon wafer, manufacturing the integrated circuits on the silicon wafer, and subsequently packaging the integrated circuit and testing the integrated circuit. When the integrated circuits are packaged, it is required to saw the integrated circuits from the silicon wafer.
When sawing the integrated circuits from the wafer, small cracks may be formed from edges of sawing, and particularly close to the edges or the corners of integrated circuits chip. The formed cracks may move towards a central circuit area of the integrated circuit, and then this situation may damage the circuit area. Thus, when cutting the integrated circuit from the silicon wafer, in order to protect the circuit area in the middle region of the integrated circuit, normally a seal ring is allocated between the circuit area and the edge of the circuit area. The seal ring may prevent any crack (e.g., a crack formed as a result of stress generated when cutting the integrated circuit from the silicon wafer) from penetrating to the circuit area in the integrated circuit. Further, the seal may also prevent moisture from penetrating to the integrated circuit, or prevent chemical substances such as acid substance or alkaline substance from entering the circuit area in the integrated circuit and then damage the circuit area.
However, fabrication materials of the seal ring are usually conductor materials (such as metals or a dielectric substrate). Though the seal ring can prevent crack from being generated when cutting the integrated circuit and prevent moisture from entering the integrated circuit chip, the seal ring may also transfer noise generated in the circuit area in the chip to external circuits or transfer external electromagnetic interference signals to the circuit area in the chip, thereby impacting upon operations of the entire integrated circuit.
Although the seal ring in the present disclosure has a technical term of “seal”, in practical implementations, the seal ring in the present application may not be completely sealed or enclosed. For example, as shown in FIG. 3 of a U.S. Pat. No. 6,492,716, a seal ring may have gap(s) or notch(s). Although moisture, acid substance or alkaline substance may penetrate through the gap portion(s), and strength of the chip resisting stress may also be meanwhile reduced, people with ordinary skills in the art should appreciate that such structure disclosed in the U.S. Pat. No. 6,492,716 should also be called a “seal ring”. Therefore, the seal ring in the present application does not exclude implementations similar to the seal ring structure which has gap(s).